| Since conventional energy resources are depleting at an alarming rate,the penetration of renewable energy is increasing greatly,but most of them has the characteristics of randomness and intermittency,leading to negative effects on power quality and reliability.Demand response(DR)programs have been investigated in recent years for providing ancillary services.Thermostatically controlled appliances(TCAs)are excellent DR resources to solve the problem of power fluctuations of tie lines caused by renewable energy because of their inherent thermal storage,wide distribution and large number of users.However,previous research works mostly focused on centralized control strategies,which rely on large-scale information exchange between the centralized controller and all the heat pump states.In the non-ideal communication environment,the centralized control strategy control effect will be seriously affected,and sometimes even failure.Motivated by the negative effects of communication quality on centralized DR control strategy and the poor real-time performance of centralized management in distribution network,the following studies are carried out:1)The basic working principle and modeling technology of TCAs are studied,and the DR characteristics are discussed.2)The direct control strategy and adjustment algorithm for heat pump load are studied.According to the characteristics of heat pumps and power system,DR analysis model of the power system in the distribution network is established.Based on the Self-regulating Distribution System Simulation Tools(SRDS),the simulation analysis and evaluation of direct load control strategy,the effect of packet loss,bit error on the control effect in non-ideal communication environment are discussed,and the compensation measures based on fitting function is put forward.3)The model prediction strategy and customers’ responsive behavior model are proposed and integrated into the original optimal temperature regulation(OTR-O),and OTR-O will be evolved into improved OTR(OTR-I).Model predication is another effective way to reduce the amount of communication data.The more simple and rapid index model is used in OTR-I to predict the equipment states to arrive at control effect as well as reduce the amount of communication data.The customers’ responsive behavior model is used to describe the effects of customers’ responsive behavior on the DR control strategy.4)A hierarchical and distributed DR control strategy is developed to surmount these deficiencies of centralized control.It is nearly a center-free algorithm and there is no need to collect the information of all houses or send control signal to everyone.Instead,all the power consumers are divided into different regions according to their geographical positions,and one aggregator is set in each region.Each region is regarded as a virtual power plant(VPP),and all VPPs are connected to the upstream power system.Therefore,the power system only needs to exchange the total power information with VPPs.The amount of communication data is decreased,and then the occurrence of packet loss and bit errors in the signal transmission is reduced.Besides,VPPs’ regulation capacities are taken into account as they can make target assignment become self-regulating and achieve maximum utilization of DR resources in controlled regions. |
